Process of making organic acids from petroleum hydrocarbons and product



Nov. 6, 1928. 1,690,769

YDRO CARBON SUPPLY 'A. W. BURWELL PROCESS OF MAKING ORGANIC ACIDS FROMPETROLEUM HYDROCARBONS AND PRODUCT Filed May 31, 1925 Gas DISCHARGE 7-PRE55URE eaves jl HYDROCfiRBON uqwm LEVEL 6/3 F ETY VA LVE REACTIONVESSEL =L TH ERMOMETEF? OXIDIZING' 6H5 SUPPLY Z};

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Patented Nov. '5, 1923.

UhllTED STATES, PATENT OFFICE,

nnrnun w. nunwnnn, or cmenm FALLS, onro, nss'rsnon, BY DIRECT AND M SNEASSIGNMENTS, TO ALOX CHEMICAL CORPORATION, OF

POBATION or m YORK.

NEW Yonx,,1v. Y., A con- PROCESS OI IAKING ORGANIC ACIDS FROM PETROLEUMHYDBOCARBON S AND- PRODUCT.

Application filed Kay 81,

invention relates to an improved 7 petroleum or distillates or fractionsthereof.

I have found that the oxidation of petroleum hydrocarbons under properlycontrolled conditions valuable organic acid products, including bothsimple carboxylio acids and hydroxy carboxylic acids, may beeconomically prepared in commercial quantities. Reference is madeparticularly to the treatment of so-called petroleum hydrocarbons, sincepetroleum oil is the principal source of such hydrocarbons at thepresent time. i The invention, however, includes the treatment ofhydrocarbons such as those occurring in petroleum, regardless of thesource from which they are obtained. It 1s noted in thisconnection thatpetroleum is a rather heterogeneous material, some of it containingprincipally paraflin hydrocarbons, while petroleum from other sourcescontains a relatively large proportion of cyclic or aromatichydrocarbons or naphthemes, and still other supplies of petroleumcontain both the paraflin and the aromatic hydrocarbons in substantialbut varying proportions. All of such hydrocarbons or mixtures may betreated in accordance with my invention with the production of organicacid products, tl'ic chemical compos1t10n and physical properties ofwhich bear a direct relation to the composition of the hydrocarbon ormixture of hydrocarbons from which they are made. I

The process consists generally in oxidizing the hydrocarbons or mixturesthereof, 1ncluding both light and heavy petroleum distillates in theliquid phase.

A feature of the invention is the production from certain hydrocarbonsof organic acids which are at normal atmospheric temperatures A furtherfeature of the invention is the production of organic acids correspondwith or bear a direct rela tion to the hydrocarbonsfrom which they arederived.

The invention will be described hereinafter by reference to theaccompanying which illustrates one form of apparatus suitable forcarrying out the oxidation process.

1923. Serial No. 642,638.

Referring to the drawing, 1 is an upright cylindrical react-ion vesselwhich may be, for example, about 17 inches in diameter and about 16 feetin height. The vessel 1 may be made of any suitable material such asiron, but preferably is made of or lined with material which isresistant to the corrosive action of the reaction mixture. An iron"essellined with aluminumgives good results,

the aluminum being very little attacked. Suitable means, notillustrated, such as a jacket surrounding the vessel or pipe coilswithin' the vessel are provided for heating and cooling the contentsthereof. At a short distance above the bottom of the vessel 1 is an airspray pipe 2. The spray pipe 2 is positioned above the bottom of thevessel in order to provide a dead space or trap therebelow, the purposeof which will be explained hereinafter. 3, 4 and 5 are a valvedhydrocarbon supply pipe, a liquid discharge pipe and a gas dischargepipe, respectively. 6 is a safety valve, 7 a pressure gauge and 8 athermometer.

The process iscarried out in the apparatus illustrated as follows:

A petroleum hydrocarbon oil, such as for example a distillate fromPennsylvania crude oil measuring 42 B. is charged into the vessel 1 upto two or three feet, more or less, from the top of the vessel, a smallamount of an oxidizing catalyst such as a compound of manganese, copperor iron, say manganese stearate, amounting to about 0.1 percent of theweight of the oil is added and the mixture heated up to a temperature inthe neighborhood of 120 C. or higher, say about 135-140 C., and anoxidizing gas, preferably air, is supplied through the spray pipe 2.Gases are permitted to accumulate in the vessel until the desiredpressure is reached, and the pressure is then maintained or regulated bycontrolling the discharge of gases through the valved outlet pipe 5. Thepressure may vary considerably, say from 250 to 320 pounds per squareinch. The preferred pressure will depend upon a number of conditions,including the temperature maintained, the kind of hydrocarbon mixtureunder treatment, the rate of air supply and, if oxygen-enriched air isused, upon the richness of the oxygen supply. The kind of apparatus,vthat is, its heat dissipating having characteristics, and the extent towhich the batch of hydrocarbon hasbeen oxidized at any particular momentalso ha7e a bearing upon the other reaction conditions. It may beexplained here that it is preferred to car out the'oxidation rocessunder such con itions that the reaction is substantiall self-sustaining;Whenusin a paratus su as that illustrated and described its walls freelyexposed to the surrounding a here, that is, unjacketed and uninsulated,and using a hydrocarbon mixture such as that referred to with a catalystand air as the source of oxygensupplied as rapidl as may be withoutcausing the body of hy bon to froth or foam to such an extent as to flowthrough the outlet pipe 5, the reaction is self-sustaining at atemperature of about 135140 C. and at a pressure of about 290-300 poundsper square inch, The reaction conditions may be va ried. For instance,it is not essential that the process be carried out underself-sustaining conditions. Heat may be be supplied from an externalsource in order to maintain the desired reaction temperature. Or the maction vessel ma be insulated. Or if the temperature of e reaction mixturetends to rise, cooling may be resorted to. The rate of reaction may beincreased by increasing the air supply or the richness of the oxygensupply or the pressure or the temperature. Oxidation apparently takesplace at all temperatures, very slowly at low temperatures and morerapidly at higher temperatures. Therefore, while I prefer to carry outthe process at a temperature at which the reaction rate is fairly rapidand the reaction self-sustaining, say 120 C. or higher, it is to beunderstood that the invention includes the employment of all suitabletemperatures at which oxidation takes place.

Dur' the oxidizing treatment, as is stated a ve, gases collecting in theupper end of the vessel 1 are released through the pipe 5. These gasescontainpractically no oxygen, a small-amount of carbon dioxid varyinfrom say 1% percent at the beginnin 0% the treatment of a batch -ofhydrocar 11 to say 7 ,5 percent near the endvof the treatment, andvarying uantities of volatile acids. The amolmt o earbondioxide formedapparently depends somewhat upon the amount of gas space in the vessel 1above the level of the liquid, the greater the space the greater thequantity of carbon dioxid produced, presumably by the oxidation ofvolatile acids in this space. The volatile acids passing off with theexit ses include a relatively large proportion of ormic acid, amountingto say 5 percent of the batch of hydrocarbons, and about 5% of othervolatile acids including acetic and propionic acids. These acids areformed in part from corresponding hydrocarbons in ,thevesell the charand apparently in ulpart from hydrocar us of higher molec ar weight.which are broken down to hydrocarbons of less molecular weight duringthe rocess. Even when the charge is substantially free of methane arelative] large quantity of formic acid is produced The pasage of air iscontinued until the desired degree of oxidation of the charge isobtained, for instance, until the oxidation is substantially complete,which condition is indicated when a sample of'the charge issubstantially completely saponifiable. The oxidation may readily becarried to the point in many instances at which only about 1 percent ofthe charge remains unmponifiable.

At the beginning of the oxidation process a portion of the mixedhydrocarbons are quickl oxidized, forming a product which is insolublein the remaining hydrocarbons. If at this point the injection of air isdiscontinued and the charge permitted to settle the insoluble productmay be drawn oil. This product is a dark-colored mass, insoluble inpetroleum, acid in nature and shows propertiw of resins and drying oils,and apparentl is a material which may be used as a substitute for resinssuch as shellac and drying oils such as linseed oil.

The oxidation is then resumed and as the oxidation proceeds an aqueousliquid highly charged with coloring matter and watersoluhle acidsamounting to as high as 30 percent of the liquid collects in the deadspace below the air pipe 2. This liquid is withdrawn from time to timeduring the rocess. By removi the highly colored hquid from the bottom ofthe vessel 1 during the oxidation process it is found that the finalproduct produced in the vessel 1 will have a much lighter color and lessodor than when the highly colored aqueous liquid collecting in thebottom of the vessel 1 is allowed to remain therein.

The acid product left in the vessel 1 after the completion of theoxidation may be refined by the usual methods, for instance, byfiltration thru charcoal, crystallization, distillation, extraction andthe like. A suitable procedure is to treat the oxidation product with asolution of caustic soda and separate the resulting'aqueoussolution ofthe sodium salts of the acids from any unsaponifiable matter and thenliberate the free acids from their sodium salts by means of a strongmineral acid such as sulfuric.

The product ordinarily comprises a mixture of simple carboxylic acidsand hydroxy acids which may be separated for instance by treating themixture with a petroleum distillate, thus dissolving the simple acidsand leaving the hydrox acids as undissolved residue. Or the hy roxyacids and simple acids ma be separated by treatment with strong sul uric[Ill . pally of solid White carboxylic acids of high molecular weightand having all of the characteristics of normal fatty acids is obtained,while from petroleum hydrocarbonsobtained from the lower district ofPennsylvania comprising a relatively large proportion of cyclichydrocarbons, a product containing some hydroxy acids and relativelylarge quantities of acids 'which appear to be formed from iso-paratfinsand which are readily converted into hydroxy acids by fur theroxidation, is obtained. The oxidation of the non-crystalline portion ofcrude oil from the lower district of Pennsylvania, such as is found inlubricating oils made from distillates which have been freed from waxand finally reduced to give oils of high viscosity and low cold test,gives practically nothing but highly hydroxylated acids which areinsoluble in petroleum, soluble in alcohol, and have the characteristicsof shellac.

As a general rule the farther the oxidation is carried, the greater isthe proportion of hydroxy acids in the product. This may be due to theconversion of simple acids to hydroxy acids during the treatment or tothe fact that the hydrocarbons which give hydroxy acids oxidize moreslowly than those hydrocarbons which give simple acids. It is noteworthyin this connection that the different kinds of hydrocarbons present in apetroleum distillate undergo selective oxidation. The first to oxidizeare those which may be separated from the distillate by treatment withfuming sulfuric acid or liquid sulfur dioxid in accordance with theknown refining methods. The oxidized product of these hydrocarbons isinsoluble in the remainder of the distillate and may be separated beforethe oxidation is continued, as is described above. The next portion ofthe distillate to oxidize is that portion which, as is described above.collects at the bottom of the vessel 1 along with water formed by theoxidation andniay be withdrawn and thus separated from the remainder ofthe distillate.

\Vhen the oxidation of a batch of mixed hydrocarbons such as a petroleumdistillate is carried substantially to completion, then i the kind ofacids produced must depend mainly upon the nature of the hydrocarbons inthe distillate. If it is desired to produce only or mainly simple acidsfrom a distillate which by complete oxidationgives more or less of thehydroxy acids, the formation of hydroxy acids may be very substantiallylimited b oxidizing only a small portion of the distil ate, say 20percent, separating the resulting acids and then repeating the treatmentof the residual portion of the distillate. By proceeding in this mannerless hydroxy acids are formed than when-the oxidation of a batch ofdistillate is completed in a single operating stage.

The results produced by the treatment of different distillates isillustrated by the following (1) Oxidaton of 42 Be. distillate fromPennsylvania crude oil.

The products are, about 5 percent of formic acid, 5 percent of acidsfrom 0 1L 0 to C ll O and 90 to 95 percent of acids having an averagemolecular weight above 300, being liquid in the mixed state and having aspecific gravity greater than 1.

Oxidation of 30-35 B. distillate from Pennsylvania crude oil.

The products are, about 5 percent of formic acid, 5 per cent of othervolatile acids and 95 to 100 percent of acids having an averagemolecular weight above 345, a specific gravity less than 1, solid at 10C. and partly crystallized at 20 C.

(3) Oxidation of wax melting at 5051 C. from Pennsylvania crude oil.

The products are, about 510 percent formic acid, 510 percent of othervolatile acids and 100-110 percent acids which are solid or semisolid atordinary temperature and resemble bees Wax in appearance and odor andhave a melting point of 45 C. and a specific gravity less than 1.

In the foregoing illustrations the products are calculated upon theweight of the hydrocarbon mixture treated.

The process of my invention is simple and inexpensive and doesnotinvolve the use of either complicated apparatus or expensive materials.It is applicable to the petroleum oils and distillates which are readilyobtainable'in largequantities and produces good yields. There is verylittle loss either by Way of. destructive oxidation or unconsumedmaterial. The products of course are of commercial utility.

This application is a continuation in part of my application, Serial No.588.073, filed September 13, 1922.

I claim:

1. Process which comprises contacting an oxidizing gas with a normallyliquid pe troleum hydrocarbon mixture in liquid phase at a temperatureabove 100 C. and at a pressure greater than atmospheric pressure but notsubstantially above about 320 pounds per square inch, producing therebyoxidation products including water-insoluble heavy or ganic acids whichare insoluble in the hydro carbon mixture, separating the insolubleacids, and thereafter during the further treatment of the hydrocarbonmixture with oxidizing gas separating aqueous liquid therefrom.

2. Process which comprises contacting an oxidizing gas with a normallyliquid petroleum hydrocarbon mixture in liquid phase at a temperatureabove 100 C. and at a pressure greater than atmospheric pressure butsubstant ally not above about 320 pounds per square inch until theformation therein of products insoluble in said hydrocarbon mixturesubstantially ceases, separating said insoluble products, continuing thetreatment of the hydrocarbon mixture with the oxidzing gas andseparating therefrom the resulting aqueous liquid.

3. Process as defined in claim 1 in which the pressure greater thanatmospheric pressurle is from 250 to 320 pounds per square 111C 4.Process which comprises contacting an ox dizing gas with a normallyliquid petroleum hydrocarbon mixture in liquid phase at a temperatureabove 100 C. and at a pressure greater than atmospheric pressure butsubstantially not above about 320 pounds per square inch, separatin theresulting insoluble material from thediquid, continuing the treatment ofthe liquid with the oxidizing gas, separating the resultin aqueousliquid therefrom, and further oontinuin the treatment of the liquid withthe oxidizing gas.

Process as defined in claim 1, in which the normally liquid petroleumhydrocarbon mixture is contacted with oxidizing gas in the presence of acompound of manganese soluble in said hydrocarbon mixture.

In testimony whereof, I afix my signature.

ARTHUR W. BURWELL.

